Drying or evaporating surface or the like



March 17, 1925.

N..TESTRUP ET AL DRYING OR EVAPORATING SURFACE OR THE LIKE Filed Oct. 4,1922 5 Sheets-Sheet 1 llll lllllllill lllllllllllllllll .l

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Patented Mar. 17, 1925.

UNITED. STATES,

PATENT OFFICE.

NILs TESTRUP, OF WESTMINSTER, LoNnoN, AND TEOFRON BOBERG, or CLAIEAM.PARK, LONDON, ENGLAND, ASSIGNORS '10 TECHNO-CHEMICAL LABORATORIES ILIMITED, OF LONDON, ENGLAND.

DRYTNG OR EVAPO'RATING SURFACE OR THE LIKE.

Application filed October 4, 1922. Serial No. 592,348.

To all whom it may concern: Be it known that we, NILs TEs'rRUr, asubject of the King of Great Britain and Ireland, and residing at 47Victoria Street, Westminster, London, S. W. 1, England, and TEOFRONBOBERG, a subject of the King of Sweden, and residing at Fairlawn,Clarence Road, Clapham Park, London, S. W. 4, England, have inventedcertain new and useful Improvements in or Relating to Drying orEvaporating Surfaces or the like, of which the following is aspecification.

This invention relates to processes or apparatus of the type in whichmoist material 1 is applied in a film or layer upon a surface for thepurpose of facilitating the transmission of heat thereto as, forexample, in drying or other heat treatment processes.

Such operations are frequently carried 2 out upon the smooth surface ofa drum to which a heating medium is supplied While it is rotated, andwhen the material undergoing treatment is in a sufiiciently liquid statea film of it may be applied by allowing the under side of the drum to dp into matter in a. suitable trough, or with matter in a more pasty orplastic condition, rollers,

spreaders or like squeezing means have been employed for compelling afilm of the mat- ;0 ter to adhere to the surface of the drum;

such expedients, however, are only satisfac tory within certain limitsof liquid content or kinds of matter and the formation .and retention ofa filmupon a surface often becomes difficult under altered conditions.

Obviously it is desirable to provide as much heating surface as possiblein an ap-' paratus of given size or cost and for this purpose it hasbeen proposed to employ two 40 drums arranged side by side and squeezingthe matter between them so as to form simultaneously a layer upon bothdrums, but this again will only apply to certain materials or conditionsthereof and materials which are difiicult to spread upon a movingheating surface in a self-retaining or adheslve film such, for example,as macerated peat of limited liquid content, lignite and the like cannotbe satisfactorily dealt with in this manner.

The object of the present invention isto overcome theforegoingdifficulties and provide for the ready filming to any desired Iextent of materials of the type indicated.

The invention consists in a method of applying and maintaining matter inuniformly and thinly distributed quantities upon a surface for thepurpose of imparting heat thereto according to which the matter isfilled into a series of grooves or indentations so formed as toeffectively retain the matter upon the surface during the operation.

The invention further consists in apparatus for applying heat, say'forexample for drying, to matter distributed upon a surface in which saidsurface is provided with closely adjacent and uniformly distributedgrooves, indentations or the like having sides so disposed as to ensurethe desired retention of the material.

The invention further consists in apparatus as indicated in which thesurface, say for example of a rotatable hollow drum, is

formed with a series of small closely spaced parallel grooves which aremore or less rectangular or parallel sided in crosssection at or nearthe bottom and flared at the top so that the adjoining sides of adjacentgrooves meet in an intermediate ridge or the like.

The invention further consists in appara-, tus for forming layers ofmoist material for the purpose of transmitting heat thereto,in whichmaterial is squeezed between a pair of rotating drums and is caused toadhere in a uniform manner to a large extent of surface by the provisionof suitably shaped, grooves in the two co-operating drum surfaces.

The invention further cons'sts in apparatus as indicated in which thematerial is suitably spread for heat transmission by a moderatetemperature difference such, for example, as may be obtained whenre-ut-iliz- .ing the latent heat of the vapour of an evaporating processor other waste or moderate temperature heat, by means of grooves whichare so shaped that the material is sufliciently wedged therein by theco-operation of the two drums to efiect its division in a uniform mannerbetween the two surfaces, thereof.

The invention also consists in improvements in or relating to spreadingmoist umterial upon heat transmitting or other surfaces as hereinafterindicated.

. Referring now to the accompanying more or less diagrammatic drawingsFigure 1 is a diagrammatic representation of two co-operating drumsWithin a casing;

Figure 2 shows the arrangement in plan view;

Figure 3 shows to a considerably enlarged scale a section of the grooveson a pair of co-operating drums;

' Figure .4 shows one condition of adjustment of the grooves of the twodrums relative to one another;

Figure 5 shows another condition of ad justment;

Figure 6 is a fragmental diagrammatic sketch showing a single drum and aplain feed roller;

Figure 7 is a fragmental diagrammatic sketch showing two drums and adividing plate between them, and

Figure 8 is a fragmental diagrammatic sketch showing'a drum withlongitudinal grooves and a brush or like dislodging or re moval means.

Figure 9 shows a modified form of the grooves and ridges.

In the convenient arrangement shown by way of example in Figures 1 and2, a is an enclosed casing within which are mounted two co-operatinghollow drums b, I) having circumferential grooves upon their externalsurfaces.

The drums b, b are provided with hollow trunnions carried in bearings 0,0 and d, d, the former of which are adjustable in a horizontal directionto regulate the distance between the axes or peripheries of the drumsand the latter of which are adjustable in an axial direction to adjustthe relationship of the grooves of one dnum relative to those of theother.

The drums are both positively driven at the same speed and in oppositerotational direct-ions by means such as those representeddiagrammatically in the drawings, such means comprising a pulley e,meshing toothed wheels f, 7, chain wheel g, g, h, h and chains 9 and kco-operating therewith.

Means such as a hopper or the like i are provided for feeding into thecasing between the two drums the material which is to be treated andwhich after treatment is removed by scrapers j, j which may co-operatewith troughs containing helical conveyors j, 7' for removing the treatedmaterial.

In the case of a drying apparatus the drums are in the first instanceheated by live steam admitted by a suitable connection to the hollowtrunnions 0, al, and as vapour is evolved from the material upon'thesurface of the drums this is drawn off through the pipe l by thecompressor k and delivered at a reduced until it is only sufficient formakeup purposes.

The circumferential surfaces of the two drums are provided with a seriesof closely adjacent circumferential grooves, asshown in Figure 3, and ofwhich say from ten to fourteen may be formed in each linear inch of thedrum length. The grooves may have a total depth somewhere in theneighbourhood of about two-thirds of the pitch and the lower portions ofthe sides of the grooves, namely the portions marked 'n, n, may beparallel or substantially parallel with one another so that the bottomof the grooves is rectangular with a width preferably equivalent toabout one-half of the pitch.

The upper portions of the sides of the grooves, namely those marked n 71are beveled for about one-half of the total depth of the groove so thatthe upper portion of the groove is flared outwards in such a manner thatthe edges of adjacent grooves meet in a V-shaped ridge midway betweenthe two grooves. Thebevelling of the flared portion may be at an angleof about 60 to the axes of the drums.

In most instances it is found that the best results are obtained whenthe ridges of one surface are set opposite to the centres of the groovesof the other surface, as shown in Figure 4, this being accomplished byadjustment of the bearings d, d. The axes of the drums may also beadjusted in relation to one another so that the ridges of one drum enterthe grooves of the other to any desired extent, say for example as shownin Figure 5, the amount of entry depending upon the nature of thematerial and/or upon the liquid content thereof.

With grooves as hereinbefore, described the material fed into the spacewhere the two drums are approaching one another is so wedged into thecavities on grooves as to present when in the initial condition ofmoisture a moderate resistance to being withdrawn, and this resistancewill be greater than the resistance to separation of the layer ofmaterial into two halves upon a plain or other contour surface runningfrom ridge to ridge of the projections between the cavities. Thedetermined layer of material squeezed between the two drums will,therefore,be divided equally between them and be distributed in auniform manner over the entire heating surface of the two drums.

Although the material is wedged in the cavities or grooves this wedgingis not suflicient to prevent its removal by toothed scraping devices,such as shownat j. j brushes or the like at any desired location afterthe material has travelled with the drums through any desired portion ofa revolution,

' the liquid content of a material asthe processmay be carried out in aseries of stages or separate pairs of drums, each of which is suitablyproportioned to the volume of the material at any particular liquidcontent, the actual condition of the material as to adhesion orfriability being practically immaterial as the grooves may be set in thecorrect relationship to one another to becapable of dealing withmaterials of very different consistencies.

In the arrangement shown in Figure 6, a single grooveddrum 0 is shown inconjunction with a plain feed roller p of smaller diameter than thedrum, this arrangement being convenient in some cases where theobtaining of a maximum surface for a given size of plant is not soessential. The mate-' rial is when treat-ed removed by a scraper orbrush 9 into the trough g from which it is taken by suitable means.

In some instances a grooved drum may be used in conjunction with aspreading plate,

' or preferably as shown in Figure 7 a spreading plate 7' may beinserted in the feed space between two grooved drums s, s which ensuresthat the pressure to which the material is subjected is the same uponbothsides of.

the plate.

Figure 8 shows an arrangement of longitudinal grooves running parallelwith the axis of the drum, and this arrangement, or grooves disposed atany other angle upon the circumferential surface of. the drum, may bedesirable in. certain connections.

Grooves of this type may be arranged to operate in conjunction with apressing plate r or a plate may be inserted between two drums, asalready described; the grooves may be of similar shape to thecircumferential grooves previously described and a brush is preferablyemployed for the removal of the material from the grooves after thedesired treatment.

The flared portion of the grooves may be curved as shown in Figure 9 andinstead of a V-shaped ridge the shape of the ridge may be rounded. Solong as a substantially parallel sided region is provided in at leastsome of the length of the grooves as shown at n if, the upper portionfollowing a curve say of radius a.

The method of heating hereinbefore described is in accordance with ourBritish Patent No. 149055, but the invention is by no means restrictedto this type of heating and may be employed in connection with many ofour prior proposals, and any hot,

gaseous or other fluid may be employed either within or upon the outsideof the drum surfaces. i

In connection with the drying of lignite exhaust steam, say, at about130 C. may often be available insuflicient quantities to perform thewhole of the drying, and in such instances this steam may be supplied tothe interior of a pair of drums and after being condensed therein may bereturned as boiler feed. A temperature of say, 115 C. may be maintainedin the casings and the evolved vapour at this temperature may be takento another pair of drums upon which drying is also carried out, thusefi'ecting a considerable economy. Similarly, suitable conditions mayalso apply in connection with the drying or other heat treatment of manyother materials.

1 Drums of this type may be operated upon the multiple efl'ect principledescribed in our British-Patent Application No. 16818 of 1922, or thedrums may be heated externally or internally by hot waste gases or anyother convenient source of heat.

The invention offers special facilities for heat treatment with smalltemperature differences as the uniform and even films or layers whichmay be obtained thereby are more readily acted upon in a satisfactorymanner. The complete operation of dispelling a large quantity of liquidfrom the material may also be divided up into a plurality of stages asthe condition of the material in the different stages will not hinderthe formation of satisfactory films becausethe grooving ensures theretention of material of practically any desired liquid content and itis possible by means of the invention to treat lignite for drying, sayfrom a wa ter content of about down to a water content of as'low as .48%if required.

By means of this invention it is not only possible to retain inuniformly distributed quantities upon the drying surface material of afriable or like nature which could not without great dilficulty' be madeto adhere to a plain surface, but the additional area afforded by thecontour of the grooves provides a much greater surface for thetransmission of heat from the material of the partition or wall into thematter undergoing treatment, and in view of this feature greatlyincreased output may be obtained from a given sizeof drum or otherevaporating surface.

The last-mentioned feature also renders the invention particularlyuseful in connection with evaporating processes where the matter remainsin a liquid state throughout the process, as not onlyis the heattransnritting sun-face greatly increased, but a given size of drum iscapable of picking up from an underlying trough or the like a muchgreater quantity of liquid than may before indicated.

The invention may be applied either to the heating only of materials,particularly where this is carried out at small temperature differences,such as are obtainable when utilizing waste heat or to drying,particularly where this is effected by re-utilizing the latent heat ofthe evolved vapour either by compression or in any other way.

It is to be understood that the apparatus and applications thereofhereinbefore described are iven by way of example only, and that moifications and additions may be introduced without in any way departingfrom the spirit of this invention.

Having now particularly described our invention what we claim as new anddesire to secure by Letters Patent is 1. Apparatus for applying heat tomatter distributed upon a surface, said surface having grooves thereinwith at least some parallel sided region in the lower portions andflaring sided upper portions;

2. Apparatus for applying heat, say for example for drying, to matterdistributed upon a surface, in which said surface is provided withclosely adjacent and uniformly distributed grooves, each having acrosssectional configuration the sides of which are parallel to oneanother in at least some region at or near the bottom and flared apartat a wider angle at the top.

3. Apparatus for a plying heat say for example for drying t e matterdistributed upon a surface, in which the surface of a rotatable hollowdrum is formed with a series of small closely spaced parallel grooveswhich are parallel-sided in crosssection at or nearthe bottom and flaredat the top so that the adjoining sides of adjacent grooves meet in anintermediate ridge or the like.

4. Apparatus according to claim 3 for forming layers of moist materialfor the purpose of transmitting heat thereto, in which material issqueezed between a pair of rotating drums and is caused to adhere in auniform manner to a large extent of surface by the provision of suitablyshaped grooves in the two co-operating drum suraces.

5. Apparatus according to claim 3 with a pair of rotating drums betweenwhich the material is squeezed, in which the material is suitably spreadfor heat transmission thereto by a moderate temperature difference, suchfor example as may be obtained when re-utilizing the latent heat of thevapour of an evaporating process or other waste or moderate temperatureheat, by means of grooves which are so shaped that the material issufficiently wedged therein by the eo-operation of the two drums toeffect its division in a uniform manner between the two surfacesthereof. I i

6. In apparatus for spreading moist material on a surfacefortransmitting heat thereto, the provision in said surface of groovesor the like having sides which are in some measure parallel or! sli htlyinclined to one another to ensure suflicient retention of the materialto complete the desired heat treatment without undesirabledisengagement.

7 Apparatus for forming layers of moist material and transmitting heatthereto comprising in combination a pair of rotatable hollow drumsarranged side by side, a series of closely adjacent and similarcircumferential grooves having at least some portion of their sidesparallel to one another formed in said drum surfaces, means foradjusting the distance between the axis and the relative' longitudinalpositions .of said drums to secure any desired co-operation of saidgrooves and their intehnediate ridges, means for feeding in material tobe squeezed between said drums into said grooves, means for impartingheat 'to said material, and means for removing the material from saidgrooves when treated.

8. Apparatus according to claim 2, in which the evolved vapours raisedin pressure and temperature so as to recover the latent heat thereof areemployed as the medium for imparting heat to the material.

9. Apparatus according to claim 3 with a pair of rotating drums betweenwhich the material is squeezed, in which ridges between the grooves ofone drum of a pair are more or less approximately complementary to oradapted to enter the grooves of the other drum and vice versa and meansare provided for adjusting the relationship of the two drums to secureany desired degree of co-operation between their grooves and ridges.

10. Apparatus for forming layers of moist material and transmitting heatthereto comprising in combination a pair of rotatable hollow drumsarranged side by side, a series of closely adjacent and similarcircumferential grooves having at least some portion of their sidesparallel to one-another formed for removing the material from saidgrooves when treated.

11. Apparatus according to claim 3, in which a pair of drums havinggrooved surfaces are separated by an intermediate smooth, surfacedplate, small roller or the like which is pressed between the drums andsupported thereby so that it is rendered sufficiently rigid to spread asmooth surfaced layer on each drum, although it is itself only ofcomparatively light construction.

12. Apparatus according to claim 3, in which the proportions of thegrooves are determined so as to spread a very thin and uniform layerover substantially all the heating surface, and at the same time retainthe material even when it has reached a comparatively low liquidcontentin order that the small temperature increase which can be economicallyobtained when employing the expedient of heating with the evolvedvapours after compression thereof may be utilized to eifect the dryingoperation.

In testimony whereof We have signed our names to this specification.NILS TESTRUP.

TEOF RON BOBERGD

